SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4dd0c904324b7c3ddfb7b97a18035717a4d26520a08733395e54f0f4c735803c' 
  AND token = '6qHbZuQ7BgCiLzHYTRvGaZbIUGz9aF6LoV5nzZIPmoc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}